First off, this is my first post. I'm very much a newbie so I apologize for my lack of knowledge.

I've been putting off buying a DSLR camera for a couple years now because the expense to get started was a little much for me with some of my other hobbies I'm already involved in.

Well, now I have my life long dream trip to Rome planned in a couple months and I'm willing to invest and get this hobbie off the ground.

I've been researching and I want to get something soon so I can play and practice. I've decided on the 600D. What I need help with are lenses. I have money to spend, but not unlimited.

All of my reseach so far is pointing me to a Sima 10-20mm due to the wide angle this lens provides so I can fit everything into the picture since Rome is cramped. I've also been considering buying and taking a EF-S 18-135mm. Based on my studies, it seems like a versitle lens.

But I've also been seeing that people recommend a 50mm for low light inside the churches and museums. Will the Sigma work well enough in lowlight so that I don't need a "nifty fifty" as they say? And what's your opinion on the 18-135mm? Would that be a wise choice for Rome? I'll be seeing the typical stuff. Museusm, churches, Coloseum, Pantheon, piazzas, fountaines, ect.

If it's practical for you to use a flash (with sufficient reach) or tripod/monopod, you can shoot at a slower shutter speed to get enough light to touch the sensor.

One thing you should bear in mind with nifty-fifties is that while they have very good low light performance, the large aperture limits depth of field (the range in which objects will appear in focus) so if you want distant and nearby subjects in focus, you'll have to stop the lens down, negating the benefit of the large aperture so in some cases, you're at no advantage (other than perhaps image sharpness) using one compared to another lens with a similar focal length.

I can't imagine the 18-135mm being a bad choice. The versatility as you put it will make it a fine choice. Rome isn't all cramped and there will be no shortage of occasions when the zoom range will come in handy.

When using a cropped sensor like the 600D lenses at about 30mm see the world in a similar way to our eyes (similar to a 50mm on a 35mm film or full frame digital camera). Anything less than this is wide so will get a lot more in but with some distortion, anything more than this is telephoto.

For a walkabout lens I use my 18-135 kit lens. Means I don't miss stuff. If your new to dslr a general purpose zoom like this or the higher quality 15-85 USM will be the right place to start.

I've found my f1.8 nifty fifty to be a bit long for a lot of stuff so I brought a sigma 30mm f1.4 that has been a joy to use and stays attached to my camera most of the time.

50mm is the perfect length for portraits on a cropped sensor. Means you don't have to be unconfortably close to the subject or too far away. With a wide angle lens you have to be 'in someone's face' to have them not to small and there will be distortion of the kind that can do things like make them look like they have a huge nose, chin or forehead.

For your trip to Rome make sure you have a general purpose walk about lens, something like the 18-135 kit lens or the slightly sharper with quieter and faster focus 15-85mm USM lens. This will be your workhorse. Everything else will be a luxury while you learn your way around your new camera

+1 to all of the above
About the 10-20 Sigma lens, it's a very useful lens to have in churches and museums but it has a learning curve attached to it. First of all it has no stabilization and in most indoor places like the ones mentioned, flash photography is not allowed, so you will have to use high ISO with this lens, which implies noise creeping in and loss of detail. For outdoors it,s excellent but you'll find that you'll seldom use the lens at 10 mm, most of the time it will be around 15 to 20 mm so for recording your trip to Rome it's redundant in my opinion. this lens has other uses where it shines, situations where you want the subject ( human ones not recommended ) in the close foreground and a very large field of view with sharp focus to infinity. Vast landscapes with something interesting in close foreground come to mind.
So you need a fast lens wide enough for cramped places and long enough if you want to reach far.
I would personally go for the 15-85 as it outperforms the others ( see Gordon's review where it compares with all the other Canon options )

Firstly, this is your trip of a lifetime so you'll want to enjoy it to the max as well as capture memories. You may well find that you're doing plenty of walking and sightseeing, and changing lenses may be inconvenient for you. If you do go down the line of getting a second lens then wider is probably a better option. As noted before, there is a steep learning curve with an ultra wide angle lens and you have to be very considered in what and how you frame an image and shoot. Very busy tourist areas may not be the best place to learn that.

50mm - as mentioned above, I think that will be too long a lens. You'll be wanting 30-35mm for capturing indoor scenes, frescos etc. That will also be an ideal focal length for when you're walking about at night in the city as well.

I'm a firm believer that you shouldn't go for too many lenses too soon. 18-135mm or even better a 15-85mm (those 3mm wider makes a big difference in the real world) would really be an ideal solution for you during the daytime, with maybe a 35mm or 30mm f1.4 for indoors or night. That way you're travelling light (leaving one or the other in the hotel, maybe) and can concentrate on taking your photos with what you have with you rather than trying to use all the lenses in your bag.

If you really get the photography bug, you'll look back on your pictures in future years and as you gain more experience you'll want to revisit to try to do more justice to your photos, but trying to juggle too many lenses and you may not like your results so much.

I think that I will only be affirming what everyone else has said here, I just have a slight different selection of lenses only do to what came with my camera and cost.

I started with a Sigma 18-125 which is very comparable to the Canon 18-135 and has been a great leaning lens and great for general walk around. This one generally stays on my camera. What you will need to learn with large focal length lenses is their sweet spots. I know my 18-125 is not at its best at the max of both ends. My next goal is the Canon 15-85 and if you have the money for the extra cost I would highly recommend it. You can get refurbished ones on Canon's site.

My low light lens is the Canon 35mm f/2. I really want the Sigma 30mm 1.4 that Ian has but I didn't have the money so I went for the cheaper but still VERY good Canon 35mm.

Also, don't skimp on a tri-pod. I got a cheap one and my camera took a nose dive within the first month and now I have to help the built in flash to pop. Manfrotto makes a great compact model for only $60.00, well worth it.

But what ever you do, get it and start practicing before your trip. I unfortunately got mine when I came back from Afghanistan then 2 weeks later went on a very important trip and was not happy. I have learned a lot since and still learning everyday. Everyone here has been great and super helpful to me. Enjoy and post us some pics from the trip.

Thanks for all the great suggestions. You guys are very helpful. I ordered the camera with the 18-135mm kit and can't wait to start practicing.
It sounds like 18-135mm is a decent beginner lens.

I'm torn about getting a wide angle like the sigma 10-20mm. I've read so many opinions about how important a lens like that is for capturing architecture in the crowded Roman streets and getting good shots of the Coliseum and large strutures without having to stitch multiple shots together. I understand that I'd need to practice if getting this lens (as well as all of them for that matter) and I plan on going to some of the local museums here as well as downtown to shoot some of the architecture. Any more thoughts on this?

As for an indoor/church/museum lens, I'm hearing a debate between the 50mm and a 30mm or 35mm. Because the camera I ordered isn't full body a 35mm, is basically like a 50mm, correct? The thing I like about the 50mm is the price is attractive. I could do the 50mm and not feel bad about getting the wide angle. Just looking up pricing on the 30mm and 35mm, it's significantly higher. Are the 30/35mm going to be that much better for my situation than a 50mm?

And do you guys have any opinions on filters? Like maybe a polarizing filter for one or more of the lenses I'm considering?

Are the 30/35mm going to be that much better for my situation than a 50mm?

In my opinion: No. It just could happen that some things are just too close and sometimes you can't step back a bit further - but in most cases I really love that 50mm focal length on the crop frame body - and it's nice for portraits (better than the 35mm in that case).

Polarizers are nice on sunny days - especially for landscapes, skies and in order to remove reflections from glass. One for the 18-135mm would be good. Some people will kill me now but in my opinion the are nice but not neccesary.

If you have the time to do this, this is the best way to figure if you want a 30, 35, or 50...Your 18-135 has all of those focal lengths I spent some time with my 18-125 at the different lengths and just shot some of the things I was interested in, this way I had a better idea of what I was looking for. I knew then that the 50 was not going to work for my situation, I'm not a portrait shooter yet and that's the only thing that "I" see a use for the 50mm right now, you may have other uses. So that cut my list to the Sigma 30 f/1.4, the Canon 28 f/1.8 and the Canon 35 f/2. As I said earlier the cost was the main reason for the 35mm; $350 vs $475 and I WILL still go back for the Sigma after I get a flash and the Canon 15-85.

I don't know anything about the 10-20 and why it requires a learning curve. Just remember, your 18-135 is still pretty wide at 18mm. Just normal shooting, I haven't found anything that 18mm couldn't handle. I have done some stitching but that was for BIG outdoor landscape shots that I knew I was going to stitch anyway and I usually shot that at the 30mm to 40mm range anyway.

With a 10-20, there are a couple of potential architectural issues. You'll have distortion but it's not pincushion and not barrel but moustache. In other words if you shoot a seascape with a horizon through the middle of the frame, it will be wavy.

It's slight, but it's noticeable. Certainly a lot more noticeable than another wide angle that has this form of distortion (the Carl Zeiss 21mm)

Similarly, when you shoot architecture you will notice slight waviness in your vertical lines. It can't be corrected in Photoshop, where barrel and pincushion distortion can.

Now if you can get over that, which I did for a couple of years, you've got a good value ultra wide angle on your hands. Sigma have two options - the f3.5 and the variable aperture. I'd go for the variable aperture as a) it's cheaper, b) it's better and c) it has a 77mm filter thread. This makes filters potentially a lot cheaper.

When shooting with any lens you'll have perspective distortion unless the lens is perfectly level (lens not pointing slightly up or down). For example, when angling the lens upwards slightly and shooting buildings the taller parts of the buildings will lean in from the edge of the frame. With an ultra wide angle this effect will be more extreme. Sometimes this can be used for effect but there will be times when you'll want to correct things in Photoshop. If so, always frame wider so you have room to correct the lean in photoshop. Preferably shoot with the lens parallel to the ground and then crop the wasted foreground in photoshop.

If you're shooting at eye level you will have a lot of wasted foreground - it's always quite useful to get down low and add an element of foreground interest into your shot as otherwise you will have nothing and then a very wide and small view of subjects in the distance. Sure, 18mm is wide enough in most instances, but the difference between 18mm and 15mm is big, then 15 to 10mm is another huge step. It will really add depth to your photos. If shooting in portrait orientation, watch your shadow and feet - they might also make a guest appearance!

If you do get one, make sure to practice before you use it to get used to the depth with leading lines to your advantage before going away - then it can be a very useful lens for you.

I have been in similar situation not long ago. I was going on longish overseas trip and could not decide which lens to take. Eventually I decided to go with 15-85 and most of the time I did not regret this decision. For my style of shooting I stayed most of the time at the short/mid range and on only few occasions I wished I had my 10-20mm with me. I would not bother with 50mm or 35, 30, etc. Both 15-85 and 18-135 are IS so low light situations are mostly covered. You can also crank up ISO. If you worry about creative use of DOF then faster lens (like plastic-fantastic Canon 50mm f1.8 ) would be required but for me it was not a consideration.